Evaluation method and device for gel state or sol-gel state change of object

ABSTRACT

The object of the invention is to solve the problems regarding the quality control of processed products (including packaged products and intermediate products during production processes) by establishing a non-destructive and non-contact type method for the measurement of gel state of a material body and a change in sol-gel state of the material body, and thereby to provide a quick automatic inspection system by which 100% inspection can be carried out easily and inexpensively on the production line. The problem is solved by observing an image formation or speckle pattern of a light section formed on the surface or observing face of the material body, using a light scattering observation system in which a coherent light (e.g., from near infrared as a laser beam) is applied to a gel material body or a material which causes a change in sol-gel state, and its reflection or permeated scattered light is image-formed by a two-dimensional image recognizing means, and analyzing and numerically treating conditions of the image (e.g., average brightness, shape, contrast of speckles and the like) and thereby evaluating gel conditions of the material body (concentration, hardness, viscosity, coagulation deterioration, texture and the like qualities and the like), conditional (quality) change from sol to gel and conditional (quality) change from gel to sol. The invention was completed by realizing a practically inexpensive, 100% inspection-performable, quick, non-contact and non-destructive automatic measuring system which is illustratively equipped with a laser beam irradiation source, a CCD camera or the like two-dimensional image recognizing means and a transferring means, can grasp an image or speckle pattern of a light section image-forming on the material body surface or light intercepting device, as a two dimensional image, and can judge the qualities of said material body by analyzing the image data.

TECHNICAL FIELD

This invention relates to a method and a device for the non-destructive,non-contact and quick evaluation of changes in the gel state and sol-gelstate of a material body capable of causing changes in the gel state andsol-gel state of a gel material body, using a two dimensionalimage-analyzing technique and making use of an image formation orspeckle pattern of a coherent irradiation light section as the index.

BACKGROUND OF THE INVENTION

Several methods are known for carrying out observation of gelationprocess or gel state based on the two dimensional light scatteringintensity. For example, there are a method for observing gelationprocess and state of a non-ergodicity sample (JP-A-2000-214086), amethod for measuring gelation degree of polyvinyl chloride(JP-A-10-120795) and the like, but these are methods for measuringluminance distribution at a predetermined scattering angle making use ofthe angle-dependency of transmitted scattered light of a thin filmsample. Some cases of the use of light scattering have been disclosed onthe analyses of agarose gel formation process (cf. homepage of OtsukaDenshi, retrieved on Mar. 16, 2002,http://www.photal.co.jp/product/calls-6-1.html) and curd formationprocess of milk (Journal of Food Science and Technology (written inJapanese), vol. 39. no. 4, pp. 309-315). However, these are also on theevaluation of scattering light intensity based on the angle-dependencyof transmitted scattered light.

In the conventional techniques, light can hardly penetrate into, forexample, a high turbidity material body or a hardly light-permeable orthick massive gel material body or gel-forming sol material body, sothat it was difficult to evaluate its angle-dependency of transmittedscattered light. In addition, there were problems in that the samplesare limited to thin sections, the device becomes complex for theevaluation of angle-dependency, it is difficult to carry out themeasurement on the production line due to a prolonged period of time forthe measurement, useful information is deleted depending on thelimitation of angle, and the like.

Speckle patters is a phenomenon in which, when a coherent light forms animage on a rough surface, it complicatedly scatters and interferes withone another depending on the roughness, so that spots having strongbrightness (speckles) are generated in a large number as a spatialdistribution of irregularly reflecting light, thus forming a spotpattern having contrast (so-called speckle pattern). For example,speckles are removed as a noise in a method in which the structure of astarch dispersion or collagen gel is analyzed by light scatteringmeasurement (JP-A-7-301602). Thus, speckle has been treated as a noiseof light and the like electromagnetic wave and supersonic wave, butmeasurements of displacement, distortion and roughness have recentlybeen introduced as its applied measuring techniques (illustrativeexamples are not described; “Practical Light Keyword Dictionary”(written in Japanese), published by Asakura Shoten, pp. 202-203). Also,its application to non-contact type migration length (speed)measurement, vibration measurement and the like based on specklepatterns has been devised in a large number. In addition, application ofa specific speckle pattern to the recognition of a material or a personhas also been devised (JP-A-2000-149087).

On the other hand, the present inventors have recently disclosed amethod for discriminating quality of gel shape food or sol shape food(Japanese Patent Application No. 2001-301653), which is a spectralabsorption method for evaluating qualities from the absorbance at aspecified wavelength of transmitted reflected light.

In this connection, virtually nothing is known about a case in whichshapes of formed image or speckle patterns of irradiated light generatedby complex scattering and interference of light are employed and appliedto the analysis of conditions of gel material bodies and changesthereof, like the invention, and completely no information is availableconcerning a case in which they were applied to gel shape food or solshape food (e.g., bean curd (tofu), soybean milk or the like).

Regarding quality of a gel shape material body such as a gel shape foodproduct, its mouth-feel is evaluated generally by synthesizing itsphysical properties, appearances (shape and color), odor and taste.Particularly, influences of hardness, elasticity and the like physicalproperties upon the mouth-feel and quality value are great. For example,packed tofu (bean curd) is produced by mixing cooled tofu with acoagulant, filling and packing the mixture and then effectingcoagulation of the contents by heating, and too soft, un-coagulated,unevenly coagulated and the like rejected articles are generated on rareoccasions due to a change in the soybean quality or an artificialmistake. In addition to this, the same problems are occurring on a largenumber of polymer gel material bodies.

Regarding material bodies which generate a sol-gel conditional change, astep for changing from sol to gel is contained in the production processof the majority of gel products, and management of the step has beencarried out relying on experience and perception of each worker. In casethat this step can be objectively measured, it will become usefulinformation on the quality control. In addition, there is a case inwhich a sol or liquid food article (a drink) becomes a rejected articledue to its gelation (coagulation) by an unexpected cause during itsprocessing process or preservation of its package. On the contrary,there is a case in which a material body which formed a gel state becomea rejected article due to its conversion into a sol state caused bystirring, external force, heating and the like.

In the case of processed products, exclusive inspectors are carrying outexclusion of rejected articles by sampling inspection (opening thepackage) or by a feel or with the naked eye without opening. However, inaddition to the personnel expenses, in case that a rejected article isshipped to the market by some chance, it will become a claiming problemand cause a danger of incurring serious damages such as reduction ofbusiness image and trust, a demand for a large security money, asuspension of business and the like.

In the case of food, hardness, taste and the like qualities are checkedby carrying out a destructive test and a sampling test through asampling inspection as a preventive measure even in the usual qualitycontrol, but this cannot be said sufficient because of the problems inthat it requires time until the results are obtained, an inspectionomission cannot be wiped out and all products of the rejected lot haveto be discarded.

However, there is no inexpensive measuring method known in the priorart, for the non-destructive, non-contact, automatic and quick judgmentof the qualities of gel state material bodies and material bodiescapable of causing changes in the sol-gel state, such as gel-shape foodand sol shape food.

In this connection, the speckle patters is defined as “A complexinterference pattern which is formed as a pattern of spots having highcontrast in the space when a rough surface is illuminated with a laserbeam or the like coherent light, due to interference of lights scatteredat respective points on the rough surface with a mutual irregular phaserelationship.” (“Dictionary of Light” published by Ohm (written inJapanese), pp. 126-127), and “When laser beam is applied to the roughgrind surface of paper, frosted glass, a wall, wood, a metal or aplastic material, a pattern of spots which cannot usually be observedshows up. Each spot is generally called as a speckle, and the pattern asa speckle pattern. This pattern is formed, because the lights scatteredat respective points on the scattering surface interfere with oneanother having a irregular phase relationship corresponding to themicroscopic irregularity on the surface.” (“Optical MeasurementHandbook” published by Asakura Shoten (written in Japanese), p. 234).

However, it is described that “Fineness of the pattern is not related tothe surface roughness and the like microscopic structures of the surfacebut determined by the shape and size of irradiated spots on the surface,and the pattern becomes rough as the spots are reduced.” and “When pintof the image formation system is turned away from the diffusing surface,the image becomes blurred, but the speckle is clear as usual.” (“OpticalMeasurement Handbook” published by Asakura Shoten (written in Japanese),p. 234).

DISCLOSURE OF THE INVENTION

The object of the invention is to solve the aforementioned problemsregarding the quality control of processed products (including packagingproducts and intermediate products during production processes) byestablishing a non-destructive and non-contact type method for themeasurement of gel state of a material body and a change in sol-gelstate of the material body, and thereby to provide a quick automaticinspection system by which 100% inspection can be carried out easily andinexpensively on the production line.

The present inventors have examined various conditions by actuallyapplying a method for the two dimensional measurement of a reflectiontype or permeation type scattered light by a coherent light to a gelmaterial body or a material which causes a change in sol-gel state, andfound as a result that the image formation and speckle pattern on theirradiation light section are reflecting qualities such as gel state,conditional change from sol to gel, conditional change from gel to sol,concentration, hardness, elasticity, tactile, mouth-feel, viscosity,coagulation deterioration and the like, thereby resulting in theinvention.

In addition, the invention was completed by realizing a practicallyinexpensive, quick, non-contact and non-destructive automatic measuringsystem which is illustratively equipped with a laser beam irradiationsource, a CCD camera or the like two dimensional image recognizing meansand a transferring means, can grasp an image or speckle pattern of alaser beam section, image-forming on the aforementioned material bodysurface or observation surface, as a two dimensional image, and canjudge the aforementioned qualities of said material body by analyzingthe image data.

That is, the invention comprises the following (1) to (7).

(1) The method for evaluating a gel state or a sol-gel state change of amaterial body described in claim 1 is characterized in that a gel stateor a change in sol-gel state of said material body is evaluated based onthe conditions of a light section formed on the image forming surface(shape, light and shade and the like) or conditions of the specklepattern (contrast, light and shade, spread and the like), using ascattered light observation system which observes, through a twodimensional image recognizing means, a gel shape or gel-forming solshape material body illuminated with a coherent light.

When a coherent light source (a light capable of performinginterference, a light having uniform phase, wavelength, amplitude andthe like), such as laser beam, is applied to the aforementioned materialbody, a reflection (or permeation) scattering of the irradiated lightoccurs on the incident side surface when said material body issemitransparent to opaque, or on the surface of an opaque memberarranged on the backside of the material body (opposite side of theincidence) when it is transparent to semitransparent close totransparent, thus forming an image of the irradiated light, and theimage is further formed on the observation surface of the twodimensional image recognizing means which observes the image. Dependingon the adjustment of aperture diaphragm, focal point and the like, imageformation of light can be effected in a space in front and in the rearof the aforementioned material body surface or aforementionedobservation surface, on the side of the image recognizing means. Onthese image formation surfaces, particularly inside of the image on alight beam surface and periphery thereof, optical path difference,direction, wavelength (frequency), phase and the like are delicatelychanged in performing complex reflection due to the irregular surfaceand inside compression, network structure and the like of the materialbody, and as a result, spots having strong brightness (speckles) aregenerated by the interference of light and an irregular pattern of lightand darkness (speckle pattern) appears. These image formation conditionsof light (shape, clearness, brightness, density, light and darkness andthe like) and conditions of the speckle pattern (shape, distribution ofbrightness intensity, density, light and darkness, contrast, clearness,spread and the like) are recognized by a CCD camera or the like imagerecognizing means which can detect it as a two dimensional image.Preferably, image data of the two dimensional distribution image ofscattered light intensity are converted into numerical values (to bereferred to as “speckle values” hereinafter) by carrying out an imagetreatment (binary treatment, edge treatment, moving treatment or thelike), a pattern recognition (e.g., use of neural network), relativepattern comparison (e.g., coinciding degree of patterns or intensitychanging degree of each picture element of the two dimensionaldistribution, in two or more of images periodically obtained with verylittle time difference), total value, average value, variance value andthe like statistical analysis treatment, linear differential, quadraticdifferential or the like multiple differential, or integration,arithmetical operation, logarithmic treatment, Fourier transformation orthe like operation treatment. Particularly, contrast of the specklepattern can be effectively expressed by a multiple differentialtreatment (e.g., linear differential or quadratic differentialtreatment). In addition, information on the gel state (compression ofnetwork structure, hardness, water holding property or the like) andsol-gel state change (e.g., gelation process, solation process and thelike of a polymer such as protein) of said material body can be obtainedfrom the aforementioned speckle values using a relational expressionconsisting between factors whose correlation was found in advance.

The generation principle of speckle pattern of the invention byreflection (or permeation) light scattering is considered as follows.The reflection (or permeation) scattered light observed by two dimensionas described in the foregoing comprises a surface reflection light inwhich a part of light complicatedly performs irregular reflectiondepending on the state of the aforementioned material body (colloidalliquid, fine network structure, rough network structure or the like) anda permeation reflection scattered light in which a part of light(particularly from long wavelength side 0.6 μm or more of visible lightto near infrared) deeply penetrates into inner part of theaforementioned material body, complicatedly repeats scattering,reflection, refraction, polarization, diffraction, absorption, diffusionand the like depending on the state of the aforementioned material body(including the state of intervening member) and then scatters again onthe surface (or the rear face or side face). These scattered lightsinterfere with each other by causing changes in the traveling direction(by angle-dependency), changes in the phase, changes in the amount ofscattered light, changes in the wavelength (frequency) and the like. Asa result, a portion having strong brightness (speckle) appears as a formof spots inside of the image formation of light formed on the surface(rear face) and observation surface of the aforementioned material bodyand the peripheries thereof. It is considered that their contrast,density, light and shade, spread, size of each speckle and the like arechanged by the qualities (inner gel structure and colloidal state andfluctuation thereof, and the like) of the aforementioned material body.A stable speckle pattern is obtained by a hard gel in such a state thatthe gel structure is contained, but the speckle pattern is loose and aptto change by a soft gel or liquid structure, and they can bediscriminated by comparing at the same exposure time (e.g., a shatterspeed of from release to 1/10,000), because the former becomes a clearimage, and the latter an unclear image due to multiple exposure.

In this connection, the observation system to be used in the inventionis a system in which an incoming irradiated light at a certain incidenceangle θ1 and a reflected (permeated) light at a certain incidence angleθ2 are observed, and the θ1 and θ2 are not particularly limited.According to the invention, it is not a method in which a light diffusedat various scattering angles is limited (extracted) to a scatteringintensity (brightness) at a certain scattering angle like theconventional method, but is a method which observes the entire imageformation broadly formed by a broad range of scattering angles from acertain observation direction. The conventional for restricting to acertain scattering angle is apt to undergo influences by heatfluctuation, structural fluctuation, irregularity of the structure,disturbance vibration and the like, thus causing deletion of usefulinformation, so that this is an unstable and inconvenient measurement incarrying out at the actual production facilities. Contrary to this, theinvention observes entire brightness distribution broadly formed by abroad range of scattering angles at one time, so that this ischaracterized in that it hardly undergoes influences by some extent ofthe disturbance of scattering angle and scattering direction, it is notnecessary to search (scan) optimum scattering angle, accurate focusingis not necessary and it can therefore be directly applied to any object.This is an effective method for material bodies whose irregularity canbe predicted, such as a material body of multi-component mixture system,a uneven material body, a material body which generates componentseparation and a material body having soft and easily warping materialand shape.

In addition, also effective is a method for taking away influence of apackaging material or for amplifying or clarifying the spacklephenomenon, by irradiating two or more of coherent lights to a materialbody. The two or more of coherent lights described in the above areirradiated by arranging two or more light sources having the same ordifferent properties (wavelength, output and the like), or as two ormore rays of light by arranging a half-path mirror or the like opticalresolution device on the optical path of the light source. For example,speckle values become more clear and stable by irradiating to the sameposition of a material body at appropriate incidence angles.

The applicable gel shape material body of the invention is a materialbody which uses water, oil, organic solvent or air as the dispersionmedium, and a protein, polysaccharide, resin or the like polymer as thedispersed phase or solute, and is a material body whose final state is asolid or gel. For example, it comprises various materials in the fieldof food, cosmetics, medicaments, inorganic gels, resins and the likeindustrial products, living body tissues, agricultural and marineproducts, liquid crystals and the like, but is generally a material inwhich a polymer is solidified (or crystallized) by forming atree-dimensional network-like or beehive-like spongy structure (thevoids are under a state of keeping a solvent in spaces of for examplefrom 0.001 to several tens μm). The surface is smooth in appearance butcan be regarded microscopically as a roughened surface similar to itsinner structure. When the gel network void of the aforementionedmaterial body is approximately from ⅛ or more to 10 times (preferably 1to 2 times) of wavelength of the irradiated light, it is under a stateof roughened surface or rough network and the invention therefore can beapplied thereto.

Examples of the gel shape material body include agar gel, gelatin gel,tofu, konnyaku (devil's tongue) jelly and the like gel shape food, gelshape hairdressing, rouge, polymer suction sheet, collagen gel and thelike cosmetics, ointment, jelly type cream, silicone gel for cosmeticsurgery and the like medicaments and medical supplies, silica gel, soiland the like inorganic gels, plastic products, tires and the likecomprising resin gels (polypropylene resin (PP), polyethylene resin(PE), low density polyethylene (LDPE), high density polyethylene (HDPE),polycarbonate resin, polyvinyl chloride resin (PVC), vinylidene chlorideresin (PVDC), polyester resin (PET), fluorine resin, acrylic resin,methacrylic resin, polyamide resin (PA), silicone resin, epoxy resin,urethane resin, melamine resin (MF), phenol resin (PF), urea resin (UF),ABS resin, polyacetal resin, polybutylene terephthalate resin, polyethersulfone resin, polyimide resin, polyether ketone resin, polysulfoneresin, polyphenylene sulfide resin, polyether imide resin, oxybenzoylpolyester resin, polylactate resin and the like biodegradable plastics,natural rubber, synthetic rubber, composite materials and foamingmaterials thereof and the like), lacquer, artificial lacquer and thelike and processed products thereof (lacquer work, paint and the like),deodorant keeping materials, human eyeballs, skin, intestinal organs,brain and the like living body tissues, rice, soybean and the likecereals, vegetables and fruits, seaweeds, fishes and shellfishes, neatand the like agricultural, marine and stock farm products, leatherarticles, wood and the like, oil and fat solidified by an oil gellingagent, emulsions, micelles (microcapsules) and the like, in whichpolymers, proteins, polysaccharides, oil and fat, surface active agents,gelling agents and the like high polymers are solidified by forming athree-dimensional network-like or beehive-like spongy structure. Livingbody tissue in which a large number of cells are assembled, coacervateby coacervation and the like can also be regarded approximately as a gelstructure, and the invention can be applied also to their formation andbreakdown.

Examples of the gelling agent include agar, starch, pine resin, oilgelling agents (12-hydroxystearic acid, paraffin wax and the like),crosslinking enzymes (laccase, transglutaminase, tyrosinase and thelike, and lipase, protease and the like whose reverse reaction showscrosslinking action) and the like industrial additives which have theaction to increase viscosity or gelation and form a three-dimensionalstructure and crystalline structure, but they are not particularlylimited. Other than these, a material which causes sol-gel shifting byheating and cooling, such as a resin, is also included. In addition, asubstance which acts upon crystallization of oil and fat like a surfaceactive agent, for example, an emulsifying agent such as polyglycerolfatty acid ester which is a large molecule and has a higher fatty acidside chain, also approximately forms a three-dimensional structure orcrystalline structure by acting upon oil and fat and emulsion.

As the sol shape material body which causes a conditional change fromsol to gel, most of the sol shape raw materials of the aforementionedgel shape material bodies are applicable. Also applicable is a sol shapematerial body which is generally liquid (sol) having fluidity andviscosity but has a property to gelatinize by an appropriate stimulus(microbial growth, enzyme reaction, heating, cooling, concentration,drying, still standing, decaying, coagulant addition, photochemicalreaction or the like) during its processing or preservation. Itsexamples include soybean milk, reconstituted soybean milk, soybean milkdrinks, high concentration soybean protein solution, raw eggs, albumen,stock material solution of tamago-dofu (steamed egg custard) or thickcustard soup, milk and processed milk drinks, agar drinks, raw starchsolution and the like sol shape food (drinks), and blood, resin powdermaterial dispersed in a solvent, starch paste and adhesive, oil gellingagent and the like, though not limited thereto. For example, a processin which soybean milk or milk is coagulated, a process in whichelasticity of dough or fish meat paste is increased during its aging,and the like are also the subjects which can be evaluated by theinvention.

On the contrary, a state in which the aforementioned gel shape materialbody changes to a sol shape by an appropriate stimulus (agitation,external force, vibration, heating or the like) is also the change insol-gel state as the subject of the invention. Like a material bodywhich shows thixotropy, this is a material body which changes to a solshape by an appropriate stimulus (agitation, external force, vibration,heating or the like), and a part of the aforementioned gel shapematerial bodies correspond thereto. For example, high concentrationcooled soybean milk gel, soybean protein gel, agar gel, gelatin gel,pectin gel and the like can be cited. Breakdown of living body cells andtissues and soil showing liquefaction phenomenon by earthquake can alsobe regarded as the material bodies which change from gel state to solstate.

In addition, it is desirable that the aforementioned material body is amaterial body in which its inner part is a uniform tissue and thesurface layer tissue of the surface or around the surface represents theinner tissue. It may also be a fibrous, filamentous, particulate,massive or the like aggregate. The aforementioned material body may beeither transparent (light transmittable) or opaque (lightun-transmittable). Particularly, this is effective also for asemitransparent to opaque gel by an embodiment like FIG. 1. When this istransparent, it is desirable to employ an embodiment in whichtransmitted scattered light is allowed to perform image formation by theaforementioned image recognizing means (FIG. 2) or a lightun-transmittable member is arranged on a place where the image formationof transmitted scattered light is effected (FIG. 3). In this connection,regardless that the surface of the member is rough surface or smoothsurface, when it is constant, relative comparison can be carried out.

Carry out of the invention can be applied to the final product or anintermediate product thereof in any process or circulation, such as fromacceptance of the raw materials to intermediate steps, before and afterthe packaging step, during storage of the stocks, before and after thetransportation and the like, in the production process and circulationof the aforementioned gel shape material body and sol shape materialbody. Said object material body or image recognizing means may beshifted (600 mm/sec or less, preferably from 400 to 10 mm/sec) at thetime of the measurement, but it is desirable to stand still from theviewpoint of reproducibility and safety.

Shape of the aforementioned material body is not particularly limited,and its examples include a cube, a rectangular solid, a column, a cupshape, a spherical shape (e.g., a spherical packed tofu packaged with abubble gum or the like material), a granular shape, a powdery shape, amassive shape, a plate shape, a fibrous (noodle) shape, a filamentousshape, a yarn shape, a cloth shape, a film shape, a tubular shape, abrow container, a bottle shape, a standing pouch and the like. Thepresence and absence of packing are not limited too, but in the case ofa packed product, it is limited to a case in which it is packed with apacking material having an area where at least a part of a light ofspecified wavelength region can pass through, arranged on any one of itstop face, side face and bottom face.

It is desirable that the aforementioned irradiation light is a lighthaving interference (coherence), monochromaticity and directivity, and alaser beam is generally most suitable. Particularly, a coherent light isapt to cause diffraction, interference and polarization through complexand delicate changes of the phase and wavelength of each reflected beamof light, penetrates into the inner part of the aforementioned materialbody depending on the wavelength, and forms a pattern of small spotshaving contrast (speckle pattern) overlapping with an image of theirradiation light section or periphery thereof on the aforementionedimage formation surface. Information on the gel state or sol state of amaterial body can be obtained by this speckle pattern or the image onthe irradiation light section.

Regarding the light source for emitting the aforementioned irradiationlight, illustratively a semiconductor laser (LD, includes a case inwhich beams of two or more wavelengths are included) is most small andinexpensive. In addition, two or more light sources having differentwavelengths may be constructed in combination to obtain more detailedinformation. In addition to this, a solid laser (Nd: YAG, Ti: sapphire,Nd: glass and the like), a liquid laser (pigment laser) and a gas laser(He: Ne, Ar, carbon dioxide, excimer laser and the like) can also beused. It is possible to use a light emitting diode (LED) and a stripetype semiconductor laser (SLD), too. Regarding the laser oscillationmethod, it may be a continuous laser or pulse laser.

Also, in addition to the aforementioned laser beam sources, a mercuryarc lamp with a combination of a Fourier transformation lens (coherenttreatment), a band pulse filter and the lie optical treatments, astroboscopic light source, a white light source (a xenon lamp or afluorescent lamp), a solar light, an incandescent light, a sodium lamp,an infrared light source (a nichrome wire heater, a ceramic heater, atungsten lamp, a tungsten halogen lamp or the like), an ultraviolet raylamp, an X ray-generating laser plasma light source and the like canalso be used as the aforementioned light source.

Regarding the classification of the aforementioned light source based onits optical axis section shape, a very small point light source, a linelight source and surface light source which become the assembly of pointlight sources (a circle, an ellipse, a spot light source, a square, aring shape and the like), a multiple line light source and the like canbe employed. In addition, a lens (a concavo-convex lens, a Fouriertransformation lens or the like), a slit plate (has one or morefilamentous holes), a pin hole plate (has one or more small holes), areflector (a mirror or the like smooth plate, a metal plate or the likerough surface plate or the like) and a light projecting method in whichthe optical axis section shape is deformed, dispersed and interfered(e.g., the use of a speckle shape irradiation light partially havingcoherence), limited or transferred by a optical fiber or the like canalso be used. Also, adjustment of the quantity of light or limitation ofwavelength or polarization may be carried out by an aperture diaphragm,an ND filter, a band path filter, a polar screen, an interference filteror the like, or a spectral means by a diffraction grating or a prism.Shape and size of the optical axis section are not particularly limitedwith the proviso that they are less than the irradiation area of eachproduct. For example, in the case of small shape products such as gelshape food, gel-formable sol shape food, cosmetics and the like, thespot shape or the like surface light source is preferably from about0.01 to about 100 mm, most preferably from about 1 to about 10 mm. Inaddition, both of the width and length of the line light source are notparticularly limited too, but a width of from 0.1 to 10 mm and a lengthof from 1 mm to 1 m are practical.

The aforementioned energy density of light is not particularly limited,but it is suitably 10 W or less and from 10 mW to 1 W. A light of morelarger output is used when it is desirable to obtain an outputsufficient for effecting its permeation into inside of theaforementioned material body.

Wavelength of the irradiation light may be within the ranges of from0.15 to 0.4 μm (ultraviolet region), from 0.38 to 0.75 μm (visibleregion), from 0.75 to 2.51 μm (near infrared region), from 2.51 to 25 μm(mid infrared region) and from 25 to 2,000 μm (far infrared region).However, it is desirable to avoid a strong absorption waveband otherthan those of dispersion media (e.g., water, an organic solvent and thelike), packing materials and dispersed phases (a polymer and the like)which constitute the material body.

The aforementioned image recognizing means for its two dimensionaldetection may be the naked eye when the irradiation light is visiblelight region, but in the case of a light of non-visible light region, atwo dimensional image recognizing means which can take a photograph ofat least a light of the same wavelength range of the irradiation lightcan be used, and its examples include a CCD (charge coupled device)camera, an MOS type camera, a TV camera, a video camera, an image tube(vidicon), an image intensifier and the like image sensors, a camera forphotographing, a digital camera and the like. Also useful are athermography, a thermocouple, a pyroelectric detector, a bolometer andthe like infrared detectors. In addition, a device in which aphotodiode, a photomultiplier (photomultiplier tube) and the like aretwo-dimensionally arranged can also be employed. In this connection, theaforementioned image recognizing means may be constructed by an imagerecognizing means limited to point shapes (pinpoint, spot and the like)and line shapes (ultra thin shape, thick band shape and the like), or bya scanning shifting means and two or more image recognizing means suchthat entire or almost entire body can be observed.

The aforementioned image recognizing means may be subjected to theadjustment of the quantity of light by an aperture diaphragm, an NDfilter or the like, adjustment of shutter speed (from release to1/20,000, preferably from 1/250 to 1/10,000), sensitivity and the likeimage recognizing means, limitation of wavelength by a band path filter,limitation of polarization by a polar screen, an optical treatment by aFourier transformation lens or the like, or a spectral treatment by adiffraction grating or a prism. Since there is a case in whichscattering wavelength and plane of polarization change to some degree asdescribed in the foregoing, it is desirable to receive broad beams oflight. In this connection, there is a case in which a polar screen isused for the purpose of controlling irregular reflection from thesurface of the intervening member. In any case, they are selected basedon image analyzing techniques and online measurement conditions so thatthe most suitable speckle pattern can be observed.

Regarding the aforementioned relational expression of speckle values andquality evaluation values, a regression expression prepared in advancebased on model data (by linear expression or quadratic expression oflinear approximate expression by the method of least squares, polynomialby multivariate analysis, logarithmic approximate expression, radicalapproximate expression, exponential approximate expression, discriminantor the like statistical analysis method), a learning structure of aneuro-computer prepared using teacher data, a theoretical expression byfuzzy logic, a theoretical expression by genetic algorithm and the likeare used. By using the relational expression, properties and qualityvalues of a material body can be obtained from the evaluation values ofthe image formation of irradiation light and speckle pattern. Inaddition, defective articles can be detected and eliminated on theproduction line by setting a threshold value.

There are various judging criteria on the gel state or sol-gel statechange of a material body as an object of the invention, such asphysical values by conventional destructive test, viscometer and thelike and subjective evaluation values of shape, fluidity and the likeappearances. For example, in the case of tofu, steamed egg custard orthe like gel shape food (opaque gel), mainly its physical properties(hardness, elasticity, water holding property, sensuous mouth feel andthe like) are large elements which decide its product value and are alsothe main qualities aimed by the invention. The conventional measurementof physical properties is carried out using a destruction tester, acreep tester, a dynamic viscoelasticity measuring device or the likeobjective physical property tester or by a subjective sensory test bysampling. The water holding property is evaluated,.for example, by theratio of loss in weight by centrifugation or spontaneous standing. Inaddition, appearances (shape, weight, color tone, gloss, texture and thelike) can also be exemplified, and a calorimeter, a color-differencemeter and glossmeter can be used too. These qualities are influenced bydelicate processing conditions such as heating, agitation, time,additive agent and the like. Changes in components are hardlyaccompanied, but, for example, differences are generated among gelstructures, and properties thereof, formed by the denaturation ofprotein or interactions of polysaccharides and the like (generally achange of a high polymer from its secondary structure to higher-orderstructure and interactions between high polymers, that is, hydrogenbonding, ion bonding, hydrophobic bonding, S—S bonding, covalent bondingand the like associations and electric repulsion). In the case of tofufor example, formation of a three-dimensional network structure by theassociation of soybean protein fine particles of approximately from 0.05to 0.1 μm through coagulation of soybean milk has been observed under anelectron microscope (cf. Soybean and Processing Thereof 1” published byKenkosha, p. 298, “Science of Food No. 29 (1976)” published byMarunouchi Shuppan, p. 43: all written in Japanese). In addition, it hasbeen observed under an electron microscope that the voids of networks ofvarious gels are within the range of approximately from 0.01 to 100 μm.

(2) The method for evaluating gel state and sol-gel state change of amaterial body described in claim 2 is characterized in that, accordingto the evaluation method described in (1), the aforementioned materialbody is a gel shape food article or a gel-formable sol shape foodarticle (includes drinks), and its quality and change in quality areevaluated.

Examples of the gel shape food include tofu, steamed egg custard,custard pudding and the like in which protein, polysaccharides and thelike high polymers are solidified by forming a three-dimensional networkor beehive structure. Examples of the gel-formable sol shape food(drinks) include tofu, a raw egg liquid, milk and the like which areliquids having fluidity and viscosity but food articles having aproperty to gelatinize by an appropriate stimulus. In addition, theaforementioned gel shape food also includes food articles which changeto a sol shape by an appropriate stimulus, such as yogurt, highconcentration soybean protein gel and the like.

Among the gel shape food articles, examples of proteinous gel shape foodarticles include silk tofu (silk-strained bean curd), packed bean curd,cotton-strained bean curd, yose tofu (oboro tofu) and the like beancurds, dough of fried bean curd such as of thick fried bean curd,nama-age, thin fried bean curd, sushi-age (a thin block of deep-friedbean curd with space for rice), ganmodoki (deep-fried bean curd mixedwith minced vegetable and seaweed) and the like, freeze-dried bean curdand dough thereof before and after freezing, sushi-age, thick fried beancurd, nama-age, thin fried bean curd, ganmodoki and the like fried beancurds, yuba (dried bean curd) and yuba-tofu, soybean protein gel,soybean milk yogurt, soybean milk jelly, bean flower and the likeprocessed food articles of soybean (includes domestic soybean, importedsoybean, soybean powder thereof, separated soybean protein, concentratedsoybean protein and the like), kamaboko (boiled fish paste), chikuwa(fish paste cooked in a bamboo-like shape), age-kamaboko (deep-friedfish paste), hanpen, fish sausage and the like fish paste products,steamed egg custard, boiled egg, custard pudding, chawan-mushi (apot-steamed hotchpotch), meringue and the like egg products, cheese,yogurt and the like raw milk processed products, gelatin, ham andsausage and the like meat processed food, wheat processed food articlesincluding noodles, fine noodles, Chinese noodles, pasta, raw wheatgluten bread (dried wheat gluten bread), gluten, bread dough, pastes ofbakery bread and biscuits and the like and bakery biscuits and the like,buckwheat dough, and jam, chocolate, gumi and the like sweets. Inaddition, examples of the starch- and polysaccharide-based gel (sol)shape food articles include cake dough such as of goma-dofu (beancustard with ground sesame), konnyaku and konnyaku jelly, tokorolen(agar having needle shape), uirou (sweet starch jelly), sweet beanjelly, rice cracker, kakiyama, cake and the like, and rice cake,goma-dofu, powdered-nut and milk jelly, bean flower and the like jellyshape food articles and the like which use a gelling agent. However, thefood articles as the object of the invention are not limited thereto.

The gelling agent is gelatin, agar, curdlan, carrageenan, starch,pectin, locust bean gum, sodium alginate or the like food additive,which is a material having thickening activity or gelling activity andnot particularly limited. In addition, tofu causes gelation alone by theaddition of an aqueous solution of a coagulant (bittern, magnesiumchloride, calcium sulfate, calcium chloride, magnesium sulfate orglucono-δ-lactone), an emulsifying coagulating agent (“Magnesfine TG”manufactured by Kao) or a crosslinking enzyme (transglutaminase;“Activa” Super Curd manufactured by Ajinomoto), and konnyaku by theaddition of milk of lime, cheese by a milk coagulating enzyme (rennet)solution and yogurt by a lactic acid bacterium or the like, and soybeanprotein gel by the heating of a 5 to 20% separated soybean proteinaqueous dispersion at 80° C.

(3) The method for evaluating gel state and sol-gel state change of amaterial body described in claim 3 is characterized in that theevaluation method described in (2) is carried out by intervening amember through which at least a portion of the irradiated light canpermeate, between the aforementioned material body and theaforementioned two-dimensional light observation system.

This case is not particularly limited with the proviso that it is amember through which at least a portion of the irradiated light canpermeate, intervened between the aforementioned material body and theaforementioned two-dimensional light observation system, for example,when the aforementioned material body as the object is packaged with apackaging material, stored in a tank or fed through a piping, or whenthe aforementioned light source and the aforementioned two-dimensionalimage recognizing means are coated. The term “a part” means a part ofthe member, a partial wavelength of the irradiation light wavelength ora portion of the irradiation light quantity. Also, though there is aninfluence of the gel structure of the aforementioned member itself, thestate of the aforementioned material body can be relatively comparedwhen the conditions are constant. In this connection, it can be mostlyignored when the gel network void of the member is ⅛ or less theirradiation light wavelength.

Examples of the material of the aforementioned member which passesirradiation light through it include glass, quartz glass, wood, paper,polypropylene resin (PP), polyethylene resin (PE), low densitypolyethylene (LDPE), high density polyethylene (HDPE), polycarbonateresin, polyvinyl chloride resin (PVC), vinylidene chloride resin (PVDC),polyester resin (PET), fluorine resin, acrylic resin, methacrylic resin,polyamide resin (PA), silicone resin, epoxy resin, urethane resin,melamine resin (MF), phenol resin (PF), urea resin (UF), ABS resin,polyacetal resin, polybutylene terephthalate resin, polyether sulfoneresin, polyimide resin, polyether ketone resin, polysulfone resin,polyphenylene sulfide resin, polyether imide resin, oxybenzoyl polyesterresin, polylactate resin and the like biodegradable plastics, naturalrubber, synthetic rubber, paper and the like members, compositematerials thereof, laminate materials, FRP materials, fibers, films,plates and the like.

The aforementioned member is used as an inspection window, packagingfilm, packaging material, coating material or printing material. Opticalfiber for propagation, optical lens, band path filter, polar screen,prism and the like auxiliary optical members are also included in theinvention. In this connection, in case that the aforementionedirradiation light permeable material and packaging material contact withfood, they are limited to the materials approved by the food sanitationlaw. In addition, limitation of the aforementioned member by thicknessvaries depending on the intensity, wavelength and the like of theirradiation light, but an irradiation light of from visible light to 2.0μm in wavelength having an output of 10 W or less can pass through awhite silicone rubber of from 10 to 30 mm and a transparent siliconerubber of approximately from 100 to 500 mm, so that any material ofseveral mm or less can be employed.

In the case of the aforementioned material body in which theaforementioned member is packaged with an aluminum deposition materialor the like non-light permeable material, the invention cannot becarried out, but it becomes possible by arranging at least a part of alight permeable moiety. In addition, a printing moiety, particularly ablack printing moiety, has a large light absorption and hardly permeableinto the inner part, but the invention can be sufficiently employed whena black printing ink permeating wavelength of a wavelength region otherthan visible light is selected. In this connection, regarding influencesof scorched marks, fried color, coloring and the like on the surface ofthe material body, information on the inside of packaged food can beaccurately obtained by avoiding their absorption wavelength regions inthe same manner. This point is the same on the aforementioned materialbodies of non-food systems.

(4) The method for evaluating gel state and sol-gel state change of amaterial body described in claim 4 is characterized in that, in theevaluation method described in (1), (2) or (3), wave length of theirradiation light is within the range of from visible light (0.38-0.75μm) to near infrared (0.75-2.51 μm).

When a light of from visible light (0.38-0.75 μm) to near infrared(0.75-2.51 μm) is used as the irradiation light like case of theinvention, not only it reaches rough face of the surface but alsopenetrates into the inner area, so that scattered light reflectingthree-dimensional structure of the gel (sol) of more deeper layer can beobtained. In addition, in case that more penetration is preferred, it isdesirable to select a light having a wavelength of from long wavelengthside of visible light to near infrared region (e.g., from 0.6 to 1.1μm), in view of the measuring sensitivity, economy and safety.

Particularly in a system containing organic matter, such as food,agricultural and marine products and living bodies, there is anabsorption wavelength region from 0.6 to 1.1 μm, which is considered tobe a secondary overtone absorption of the bonding of solutes (protein,polysaccharides and the like). When an irradiation laser beam havingthis range is used, influence of water as the solvent is small, and itpenetrates into more deeper layer (several mm to several 10 cm from thesurface layer), so that scattered light reflecting the state of theinner gel structure can be obtained. Since very complex scattering isrepeated, a speckle pattern having more clear contrast can be obtainedeasily, in comparison with the surface scattered light (cf the principleof speckle pattern generation in the aforementioned paragraph number0019). For example, in the case of packed tofu, almost all of its innerportion, approximately 100 mm in depth from the surface layer of themeasuring face, at least from 1 to 50 mm, can be evaluated by a laserbeam having a wavelength of from 0.6 to 1.1 μm (output 1 W).

In the case of tofu (or soybean milk) for example, easily absorbablewavelength is mainly from 0.6 to 1.3 μm, and a wavelength of this rangeeasily penetrates into the inner portion so that the invention can becarried out easily. In addition, the absorption wavelength ofpolypropylene containers is a broad range of from 0.6 to 2.0 μm, andlonger wavelength becomes difficult to be absorbed. Accordingly, it isdesirable to select a wavelength of within the range of from 0.6 to 1.3μm for the tofu in a polypropylene container. In this connection, awavelength of 1 μm or less is practical from the viewpoint that aninexpensive image recognizing means having sensitivity to that regioncan be employed. However, when an inexpensive system can be realized inresponse to the future technical advance, it may not be limited to thesewavelengths.

However, in case that the aforementioned material body has aparticularly high water content (e.g., a water content of 60% byweight), there are large absorbance of water (e.g., 1.2 μm, 1,45 μm,1.94μ and the like in the long wavelength infrared region, and there areinfluences of the atmospheric temperature and infrared radiation, sothat it is desirable to avoid it to the best. In addition, it isdesirable to the best to avoid absorption wavelengths of membersblocking the aforementioned material body, such as a packaging material,a printing paint and the like, and outer skin tissues (scorching,staining). In this connection, ultraviolet rays are absorbed by plasticand glass product materials, and infrared rays are absorbed by glassproduct materials.

In addition, it becomes unnecessary to set the aforementioned scatteredlight observation system in a dark room, by avoiding emission wavelengthof stray light such as of natural light, interior illuminations(fluorescent light, mercury light) and the like. In this connection,when influence of stray light is avoided, it is desirable to select awavelength region by avoiding the emission wavelengths of visible lightregion and outer light sources (fluorescent light, mercury light and thelike).

In general, the near infrared region is minutely divided generally into3 sections of a wavelength region 1 (combination tone region) of from1.8 to 2.51 μm, a wavelength region 2 (primary overtone region) of from1.4 to 1.8 μm and a wavelength region 3 (secondary overtone region) offrom 0.75 to 1.1 μm. It has been reported that the use of the wavelengthregion 3 having high permeability is desirable in the case of themeasurement of chemical components, particularly suited for a foodarticle having a water content of 80% by weight or more (Tetsuo Sato,Abstract of Papers, 5th Non-destructive Measurement Symposium, pp. 8-14;Iwamoto and Uozumi, Japanese Society of Food Science and Technology,vol. 32, no. 9, pp. 685-695). According to the invention, the longwavelength side of visible light also has the same property of theaforementioned near infrared wavelength region 3, so that the range offrom 0.6 to 1.1 μm as described in the foregoing is desirable as thewavelength capable of carrying out the invention.

(5) The method for detecting free water in gel shape packaged fooddescribed in claim 5 is characterized in that, in the evaluation methoddescribed in (2), (3) or (4), free water presenting in the inner part(measuring surface) of a product which passed a step for contacting withwater after sealed packaging of the aforementioned material body isdetected, for example, in case that it is a defective product in whichwater is soaked into its inner part due to pin hole, cracking,insufficient sealing and the like on the packaging material or in casethat release of water is generated due to low water holding property ofthe gel.

In this connection, any method can be employed as a method forcontacting a packaged product with water, such as methods for soaking ina steam heating tank, hot water tank, cooling water tank or the like,carrying out water jet showering or spraying with water or steam.

This invention is based on the fact that the speckle pattern isabnormally stressed and becomes clear (increase of speckle values) dueto further increased complex refraction of the aforementioned reflectiontype scattered light when a thin water layer is present between apackaging film and a gel material body. Though a dedicated pin holedetector of vacuum type or electric system is on the market, theinvention is valuable in view of the point that it can be measuredtogether with the inner qualities.

(6) The method for evaluating gel state and sol-gel state change of amaterial body described in claim 6 is a method for carrying out theevaluation method described in (1), (2), (3), (4) or (5), which is amethod for evaluating a material body characterized in that theaforementioned material body is made into a dynamic state. This is amethod in which, when made into the aforementioned dynamic state, aspeckle pattern or the like image is observed by an image recognizingmeans while applying a micro-vibration, excitation, reciprocation, soundwave, supersonic wave, air- or water-spraying or the like external forcecontinuously or intermittently, or just after termination of theexternal force. The inertia force when a material body is moved,accelerated, decelerated or stopped on a conveyor can also be used. Inaddition, a very little vibration by a pulse laser can also be used.Since the change in speckle pattern by dynamic state differs dependingon the hardness or softness of the gel state or sol state material body,it becomes easy to obtain correlation with hardness (breaking force).

The ultrasonic oscillator has a frequency of 20 kHz or more, preferablyfrom 20 to 50 kHz, and an output of 0.2 W/cm² or more and 100 W/cm² orless, preferably from 0.5 to 10 W/cm², and the ultrasonic vibrator isarranged, for example, by contacting to a conveyer on which theobjective material body is mounted or to the objective material body. Inaddition, it is possible to take an embodiment in which the materialbody or its bearer (a conveyer or the like) is vibrated or reciprocatedin the mono-axial direction, biaxial direction or tri-axial direction.As the vibration apparatus, any one of a magnetic system, excitationsystem, pneumatic system, hydraulic system and the like methods can beused. Frequency of the vibration is from 5 to 5,000 Hz, displacement isfrom 10 to 5,000 μm, speed is from 1 to 10,000 mm/s, acceleration isfrom 1 to 100,000 m/s² and impact vibration power is from 0.5 kN to 30kN, but preferably, the frequency is from 5 to 400 Hz, displacement isfrom 20 to 500 μm, speed is from 10 to 200 mm/s and acceleration is from20 to 1,000 m/s²

(7) The device described in claim 7 for carrying out a method forevaluating gel state and sol-gel state change of a material body is adevice for carrying out the evaluation method described in (1), (2),(3), (4), (5) or (6), characterized in that the aforementioned materialbody constituting at least one row in the transverse direction against amoving direction, the aforementioned light irradiation device whichirradiates a light having at least one spot shape or line shape sectiontraversing the moving direction (this may be fixed to or separated froma light irradiation photographing device prepared by arranging at leastone of the aforementioned two-dimensional image recognizing means) or atleast one of them is moved by a moving means, thereby carrying outscanning measurement of almost full face or full face of theaforementioned material body.

In this connection, the moving means is not particularly limited withthe proviso that it can effect relative movement of the aforementionedmaterial body and aforementioned light source. Regarding the twodimensional image recognizing means, there is a case in which it isfixed alone to photograph whole body of the aforementioned material bodyor a case in which it is fixed with a light source and simultaneouslymoves, but in any case, the invention can be employed when it is amethod capable of scanning and photographing the full face or almostfull face.

The moving method may be a continuous, intermittent or the like methodand is not particularly limited. In addition, as shown in FIG. 10 toFIG. 13, the aforementioned material body may be standing still orflowing in a container, a tank, a piping or the like.

In the case of an automatic measurement, for example, primarydifferential values of the brightness of respective picture elements(e.g., differences in the brightness of respective picture elementsadjoining in the traverse direction or values obtained by dividing thedifferences by inter-picture element distances are totaled, thecalculation is repeated in the longitudinal direction, and then allvalues are totaled) is calculated on the two-dimensional image dataobtained from the speckle pattern and image formation of irradiatedlight (about 10 milliseconds as the required time for 1 measurement, avery short period of time of from 1 millisecond to 100 milliseconds per1 performance including times for data communication and calculationtreatment). The above measurement is continuously repeated twice ormore, preferably 10 to 50 times, and the average value of the calculatedvalues obtained by respective measurements is used as the result of onemeasurement. Particularly, clearness and contrast of the speckle patterncan be expressed by the primary differential values. A system foroutputting quality indexes of a material body, discriminating rejectedarticles or excluding them from the line by an exclusion means isassembled, based on the aforementioned relational expression preparedfrom the numerical values obtained by the calculation treatment andseparately measured quality index values of the material body. Sincesuch a system is a non-destructive, non-contact, inexpensive and quicksystem, 100% inspection can be carried out at a high speed on theproduction line.

Thus, according to the invention, the measuring time is markedly shortwhich is 1 to 2 seconds or less, generally from several 10 to several100 milliseconds. Even when there is a change in the aforementionedmaterial body, such as a scattered light angle-dependent or thermalfluctuation or a static fluctuation accompanied by a structuralirregularity, such a change within the measuring time is almostnegligible. Even in case that there are some influences, it is notnecessary to take them into consideration because they are treated byaveraging them. In addition, even when the scattering angle is changedin each measurement to some extent, it is a degree of somewhat changingthe position of speckles, so that only a very little influence isexerted upon contrast and the like of the speckle pattern.

In the actual measurement in the field, a period of time is requireduntil the observed values are stabilized, due to vibration of machinesin the surroundings, swaying of the aforementioned material body and thelike. In general, the measurement is carried out twice or more,preferably 10 to 100 times, under such a state that the observed valuesare stable, and an average value (or an intermediate value) of the thusobtained aforementioned speckle value data, if necessary after excludingabnormal values, maximum value, minimum value and the like, is used asthe central value. In case that the measurement is carried out byrepeating two or more of the measurement, the duration becomes from 10milliseconds to 10 seconds. In addition, by deducing final observationvalue from the observation value increasing rate or accelerating rateuntil the aforementioned observation values become stable, one measuringtime can be further shortened so that a high speed measuring system canbe constructed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanatory drawing of the two-dimensional observationsystem of reflection type scattered light described in claim 1 andExample 1 of the invention (image formation on the surface of theaforementioned material body was photographed),

FIG. 2 is an explanatory drawing of the two-dimensional observationsystem of reflection type scattered light described in claim 1 andExample 1 of the invention (image formation on the rear face of theaforementioned material body was photographed),

FIG. 3 is an explanatory drawing of the two-dimensional observationsystem of permeation type scattered light described in claim 1 of theinvention (image formation of scattered light permeated trough theaforementioned material body on the rear face was photographed),

FIG. 4 is an explanatory drawing on the relationship between hardness ofa gelatin gel and speckle value (observed value) described in claim 1and Example 1 of the invention,

FIG. 5 is an explanatory drawing on the relationship between hardness ofan agar gel and speckle value (observed value) described in claim 1 andExample 1 of the invention,

FIG. 6 is an explanatory drawing on the relationship between hardness ofa coffee-containing carrageenan gel and speckle value (observed value)described in claim 1 and Example 1 of the invention,

FIG. 7 is an explanatory drawing on the relationship between hardness ofan albumen gel and speckle value (observed value) described in claim 1and Example 1 of the invention,

FIG. 8 is an explanatory drawing on the relationship between hardness ofa packed tofu and speckle value (observed value) described in claim 1and Example 2 of the invention,

FIG. 9 is an explanatory drawing on the relationship between hardness ofa hot packed tofu and speckle value (observed value) under packagedstate and unsealed state described in claim 2 and Example 3 of theinvention,

FIG. 10 is an explanatory drawing of the sol-gel state change measuringembodiment (box type, small scale batch system) described in claim 1,claim 2, claim 3 and Example 4 of the invention,

FIG. 11 is an explanatory drawing of the sol-gel state change measuringembodiment (tank, large scale batch system) described in claim 1, claim2, claim 3 and Example 4 of the invention,

FIG. 12 is an explanatory drawing of the sol-gel state change measuringembodiment (piping, inline continuous system) described in claim 1,claim 2, claim 3 and Example 4 of the invention,

FIG. 13 is an explanatory drawing of the sol-gel state change measuringembodiment (probe system sensor) described in claim 1, claim 2, claim 3and Example 4 of the invention,

FIG. 14 is an explanatory drawing on the speckle value (observed value)which changes by the gelation step and gel state of a gel formable solshape food article, described in claim 3 and Example 4 of the invention,

FIG. 15 is an explanatory drawing on an embodiment of the device (linearlight source) described in claim 7 and Example 7 of the invention,

FIG. 16 is an explanatory drawing on an embodiment of the device(transverse line arrangement of spot light source) described in claim 7and Example 7 of the invention,

FIG. 17 is an explanatory drawing on an embodiment of the device(two-dimensional arrangement of spot light source) described in claim 7and Example 7 of the invention,

FIG. 18 is an explanatory drawing on the detection of a heterogeneouspart of a material body, described in claim 7 and Example 7 of theinvention,

FIG. 19 is an explanatory drawing on the relationship between hardnessof a packed tofu and speckle value (observed value) under an excitationcondition, described in claim 6 and Example 6 of the invention, and

FIG. 20 is an explanatory drawing of an inspection device system intowhich a two-dimensional observation system of reflection type scatteredlight was built, described in claims 1 to 7 and Examples 1 to 7 of theinvention.

Regarding the reference numerals and signs in the drawings, 1 is amaterial body, 2 is a coherent irradiation light, 3 is a light source, 4is a surface reflection type scattered light, 5 is a permeationreflection type scattered light, 6 is a speckle pattern, 7 is an imageformation on the observation surface, 8 is an image formation on thematerial body surface, 9 is two-dimensional image recognizing means, 10is an aperture diaphragm, polar screen, band path filter or the likeoptical auxiliary part, 11 is a condenser lens, diffusion lens or thelike optical auxiliary part, 12 is a Fourier transformation lens, polarscreen, band path filter or the like optical auxiliary part for opticaltransformation or limitation use, 13 is a line, spot or the like opticalaxis transformation lens, slit plate or the like optical auxiliary partfor optical axis shape transformation or limitation use, 14 is a devicefor agitation use, 15 is a container (box) for a gel shape material bodyor a material body capable of causing a gel-sol state change, 16 is acontainer (tank) for a gel shape material body or a material bodycapable of causing a gel-sol state change, 17 is a container (piping)for a gel shape material body or a material body capable of causing agel-sol state change, 18 is an inspection hole, 19 is a moving means, 20is an image of linear irradiation light, 21 is an optical fiber forirradiation light use, 22 is an optical fiber for image light (lightinterception) use, 23 is a tuning conveyer, 24 is a main body (detectingelement) conveyer, 25 is a shake off conveyer, 26 is an operationcontrol panel, 27 is a shake off device, θ1 is an angle of incidence(vertical line on the contact surface of incident light axis andirradiation site of an object to be treated, so-called angle of normalline), θ2 is an angle of reflection (transmission) (vertical line oflight-intercepting light axis on the contact surface of reflection siteof an object to be treated, so-called angle of normal line), A is amoiety of a speckle pattern having strong contrast (hard), and B is amoiety of a speckle pattern having weak contrast (soft).

BEST MODE FOR CARRYING OUT THE INVENTION

As shown in FIG. 1, the principal part of the embodiments described inclaims 1 to 7 of the invention is constituted by a two-dimensionalscattered light observation system equipped with a light source 3 whichapplies a coherent light 2 to the aforementioned material body 1 atangle of incidence θ1 (e.g., 0°≦θ1<critical angle<90°) and atwo-dimensional image recognizing means 9 that observes a surfacereflection type scattered light 4 emitting from the surface of theaforementioned material body 1, a permeation reflection type scatteredlight 5 once permeated into the inner part and again reflected therefromand an interference speckle pattern 6, at an angle of reflection(permeation) θ2 (e.g., 0≦θ2≦180°). The observation angle is 0≦θ3≦180°.

In the case of the measurement of reflected light, the angle ofincidence θ1 is generally 0°θ1<90° (provided that θ1 <critical angle,and strictly, θ1 is adjusted such that it becomes smaller than thecritical angle determined by respective index of refraction at theinterface between air and a packaging material and at the interfacebetween the packaging material and the inner material body), preferably20°≦θ1<70°, and the angle of reflection (permeation) θ2 is 0°≦θ2<90°,preferably 0°≦θ2<70°. In some cases, it is desirable to avoid totalreflection. Total reflection occurs when normal line is contained in theface composed of the incidence light axis and light-intercepting lightaxis, and θ1=θ2. The observation angle θ3 is 0≦θ3<180°, preferably20°≦θ3<140°.

In the case of the measurement of transmitted light, the angle ofincidence θ1 is 0°≦θ1<90° (θ1<critical angle), preferably 20°≦θ1<70°,similar to case, and the angle of reflection (permeation) θ2 is0°≦θ2<180°, preferably 20°≦θ2<180°. The observation angle θ3 is0≦θ3<180°, preferably 20°≦θ3<180°. Permeation measurement of θ1=0° andθ2=0° is similar to the reflection measurement but, for example, is acase in which the incidence light axis and light-intercepting light axisare parallel and the incidence site and light-intercepting site aredifferent from each other.

It is also effective to change the light 2 emitted from the light source3 into an appropriate coherent light via the Fourier transformationlens, polar screen, band path filter, reflecting mirror (smooth surfaceor rough surface), photo-refractive crystal filter, interference filter(obscure glass, a resin, a gel shape material, a colloid particledispersion or the like) or the like optical auxiliary part 12 foroptical transformation or limitation use, or the line, spot or the likeoptical axis transformation lens, slit plate or the like opticalauxiliary part 13 for optical axis shape transformation or limitationuse.

It is also effective to process or limit the light interception (image)via the aperture diaphragm, polar screen, band path filter or the likeoptical auxiliary part 10 or the condenser lens, diffusion lens or thelike optical auxiliary part 11, before the two-dimensional imagerecognizing means 9.

The aforementioned surface reflection type scattered light 4 is anirregular reflection light scatters at random on the material bodysurface (diffused reflection light, not related to the angle ofincidence θ1) and causes mutual and complicated interference with thepermeation reflection type scattered light 5 when a light penetratesinto inside of the aforementioned material body to cause complextransmission, scattering, refraction, dispersion (spectral action),diffraction or polarization and again scatters at the angle ofreflection (transmission) θ2, and as a result, the image formation 8 onthe material body surface (upper surface on the material body in FIG. 1,or lower rear face on the material body in FIG. 2 and FIG. 3), imageformation 7 on the observation surface or speckle pattern 6 is formed.In this connection, θ2 may not always the same as θ1. In addition, theembodiments of FIG. 2 and FIG. 3 are embodiments which can be carriedout particularly when the material body is semi-transparent totransparent.

Regarding the aforementioned two-dimensional image observation system,it is possible to employ an optical fiber-mediated embodiment due to thenecessity to carry out remote measuring for the explosion-protection anddrip-proof purposes or an embodiment as a small probe shape whichdirectly contacts to the aforementioned material body (FIG. 13), inaddition to an embodiment in which the laser beam source 3 and the CCDcamera 9 for example are arranged in the space on the aforementionedmaterial body. In these cases, a form in which the aforementionedtwo-dimensional image observation system is coated with a irradiationlight-transmittable member is desirable. This can be applied to inlinemeasurement, explosion-protection, drip-proof and the like purposes andis one of the embodiments of the invention, and though being aliquid-contacting type, this can be regarded as a non-contact meansmediated by the aforementioned member.

Examples of qualities which are not the object of the invention includegenerally shapes (size, weight, missing and the like), taste and thelike chemical quality items. It is possible to construct a syntheticquality measuring system by combining with other optical, chemical andphysical methods.

On the other hand, in carrying out the invention, a phenomenon was foundin which the brightness (or absorbance or reflection light quantity) andshape of the image formation 8 of the irradiation light section on thematerial body surface are changed by the concentration (concentration ofsolid contents) of the aforementioned material body. That is, light andshade (concentration of solid contents) of the aforementioned materialbody can be predicted from the changed amount of its image. For example,in case that the image formation 8 of the irradiation light section isan ellipse, the image formation gradually becomes circular and then anunclear shape as the concentration of solid contents increases. Usefulinformation can be simultaneously obtained also from the image formationof the irradiation light section in combination with the specklepattern.

In addition, in carrying out the invention, another phenomenon was alsofound in which, when the aforementioned material body is an O/W or W/Otype emulsion having a turbid state of water phase and oil phase, thebrightness and shape of the aforementioned image formation itself byirradiation light or the speckle pattern are changed in response to itsemulsion dispersion condition and particle size distribution. That is,particle size distribution and particle size change in theaforementioned material body can be measured based on the changedquantity. For example, the speckle pattern of irradiation light showsclear contrast when rough particles are frequent, and an unclear patternis observed in the case of fine particles. Conventionally, in carryingout measurement of a thick emulsion by particle size distributionmeasurement based on a transmitted light scattering method, there was adisadvantage in that its state is somewhat changed due to the necessityto dilute it with a solvent. By applying the invention, state of a thickemulsion can be monitored directly or real time.

EXAMPLES

The invention can be carried out, for example, by the embodiment shownin FIG. 20. This is constituted from a tuning conveyer 23, a main body(detecting element) conveyer 24, a shake off conveyer 25 and anoperation control panel 26, the light source 3 and image recognizingmeans 9 are arranged in one set or more in the main body, and forexample, the material body of object is received from asupplying-transferring conveyer by a stopper of the tuning conveyer 23and transferred to the main body conveyer 24, and then, for example,light from the light source 3 is applied to a side face of the materialbody of object and its image is image-photographed by the imagerecognizing means 9, thereby effecting the measurement. At the time ofthe measurement, said material body of object 1 may be moved (600 mm/secor less, preferably 400 mm/sec), but it is desirable to allow it tostand still in view of reproducibility and stability. After themeasurement, samples are transferred from the main body conveyer 24 tothe shake off conveyer 25, and a material body whose measured result wasjudged, for example, good (a gelatinized article or coagulated article)proceeds to the next step, but a material body judged as a defectivearticle (an un-gelatinized article or un-coagulated article) iseliminated by the shake off device 27. Adjustable setting of thetreating capacity can be made, for example to a number of from 1,000 to10,000 samples per 1 hour, by controlling the number of material bodiesto be transferred to the main body conveyer 24, conveyer speed and thelike. In addition, it is possible to correspond to from a thinninginspection to the 100% inspection when light sources and cameras arearranged in response to the number of samples. In this connection, theembodiment of FIG. 20 is an example of the embodiments of the inventionand not particularly limited thereto.

The laser beam source 3 is a semiconductor laser (MLX manufactured byKMKO GIKEN, oscillating power 30 mW, spot light is an ellipse of 3×6 mm,no lens head, and the irradiation wavelength is for example 0.67 μm,0.78 μm, 0.82 μm, 0.85 μm or the like), which was applied to the surfaceof the aforementioned material body at a angle of incidence of about30°. As the two-dimensional image recognizing means 9, a CCD camera (XCmanufactured by SONY, 1 picture element 10 μm, 350,000 picture elements,and a light intercepting wavelength of from visible light to nearinfrared region was used) was used and light interception on the surfaceof the aforementioned material body 1 was effected at an angle ofreflection of about 0°. This was focused on the image forming surface 8of irradiation light, namely on the surface of the aforementionedmaterial body in the case of a semi-transparent to opaque gel as shownin FIG. 1, or on the rear face of the aforementioned material body inthe case of a transparent gel as shown in FIG. 2. In this connection, adarkroom condition was not employed for particularly shutting out theoutdoor daylight in carrying out the photographing, and the measurementwas carried out under an interior light. Regarding the speckle pattern 6of the thus obtained image data, an average value of the total value ofdifferential values obtained by 30 times of the measurement was used asthe speckle value as described in the foregoing. Correlation analysis,multiple regression analysis and analysis of variance were carried outon the relationship between this speckle value and the conventionalanalytical values using a commercially available statistical analysissoftware (EXCEL 2000 manufactured by Microsoft, or the like) to obtain amultiple regression expression and an approximate expression.

In this connection, the light source and image recognizing means and thecalculation methods for data treatment and numerical treatment are notlimited thereto.

Various conditions were examined in the invention, and found that theaforementioned speckle value has a high correlation with the gel stateor sol-gel state change of material body. That is, examination was madeon the correlation between speckle values under sol state, gel state,sol-gel intermediate state and the like various states and fractureforce value, concentration, mouth feel and the like qualities. As aresult, the contrast became clear and the speckle value became large asthe gel became hard, thus showing a high coefficient of correlation.Also, a semi-mature or sol state gel showed a blurred speckle patternand therefore can be easily distinguished with the naked eye from a hardgel. In the same manner, there was a tendency to show the specklepattern in broader range, and the contrast strongly, during the processof changing from a sol state to a gel state, and further from a soft gelstate to a hard gel state. Also, a relationship was found between theaverage value of brightness which represents light and shade of specklepattern and the hardness, obtaining a result that the darker, theharder. In addition, there was a tendency that shape of the imageformation of an oval irradiation light section becomes close to completeround, for example, as the solid content of a gel becomes large.

The following describes Examples which used the two-dimensional imagerecognizing systems of scattered light as shown in FIG. 1 and FIG. 2, ona packed tofu prepared by mixing a cooled soybean milk with a coagulant,filing and packaging the mixture and then heating it to effectcoagulation, a hot packed tofu prepared by mixing a hot soybean milkwith a coagulant and then filing and packaging the mixture, an albumengel, a gelatin gel, an agar gel and a coffee-containing carrageenan gelas examples of the gel shape material body, and a polyethylene resin asan examples of the resin.

Example 1

Regarding the gelatin gel, 0, 3.5, 8.8, 17.5 or 35 g of a gelatin powder(an article on the market) was weighed, swelled with a small amount ofwater, adjusted to a total volume of 350 ml by adding boiling water,dissolved by stirring and filled in a semi-transparent pack made of PP(2B size, 300 ml capacity), and then the pack was heat-sealed with anNY/PP film and put in a refrigerator overnight to effect gelation.

Regarding the agar, 0, 0.17, 0.34, 0.86, 1.75 or 3.5 g of an agar powder(an article on the market) was weighed, adjusted to a total volume of350 ml by adding boiling water and then gelatinized in the same manneras the case of gelatin.

Regarding the carrageenan gel, 0.17, 0.34, 0.86, 1.75, 3.5 or 7 g of acarrageenan powder (manufactured by Okuno Seiyaku) was weighed, mixedwith 1.5 g of a soluble coffee powder (an article on the market),adjusted to a total volume of 350 ml by adding boiling water and thengelatinized in the same manner as the case of gelatin.

Regarding the albumen gel, 3.5, 8.76, 17.5 or 35 g of an albumen powder(manufactured by Okuno Seiyaku) was weighed, adjusted to 350 ml byadding cool water and then subjected to 1 hour of heat coagulation in awater bath controlled at 80° C. This was cooled with ice water and thenrefrigerated overnight.

Each gel sample was allowed to stand still with the film face orcontainer bottom face upward (pack surface), and the speckle pattern 6was observed using the semiconductor irradiation light 2 of 0.67 μm inwavelength and using the aforementioned scattered light two-dimensionalobservation system (FIG. 1). Thereafter, each sample was unsealed and,as it is in the container, subjected to the measurement of fractureforce (a 23 mmφ plunger is penetrated at a speed of 6 cm/min, and thestress at the time of fracture is measured) using a rheometer(NRM-2002J, manufactured by Fudo Kogyo). The results are shown in Table1 and FIG. 4 (gelatin gel), FIG. 5 (agar gel), FIG. 6 (coffee-containingcarrageenan gel) and FIG. 7 (albumen gel). TABLE 1 ConcentrationFracture force Speckle value % gf/cm² Pack surface Pack rear faceGelatin gel 10.0 519.5 5100 6300 5.0 197.4 3600 4500 2.5 47.2 3300 38001.0 1.0 2300 3600 0.0 0.0 2100 2500 Agar gel 1.0 134.8 5000 7300 0.525.9 4400 7000 0.2 4.8 4000 3700 0.1 1.0 4000 3300 0.0 1.4 2500 2900 0.01.0 2100 2500 Coffee-containing carrageenan gel 2.0 662.1 3450 1.0 105.93050 0.5 17.5 2600 0.2 3.9 2600 0.1 0.5 2400 0.0 0.1 2000 Albumen gel10.0 478.5 5500 5.0 16.7 4330 2.5 0.5 2340 1.0 0.5 1840 Polyethyleneresin Ultra high density hard 27620 High density slightly hard 25930Expanded soft 13950

On the other hand, using commercially available polyethylene resins,namely an ultra high density polyethylene resin (molecular weight3,000,000 or more; UHMW), a high density polyethylene resin (molecularweight 1,000,000 or more; HMW) and an expanded polyethylene resin (B-4;slightly soft), their smooth surfaces were directly observed to measurespeckle values in the same manner, with the results shown in Table 1. Inthis connection, it can hardly be expressed by figures, the specklepattern of UHMW was fine, and that of HMW was rough, when their imagestates were observed. Based on this, the invention can also be appliedto the evaluation of compression density of polymers.

In the case of the gelatin gel, measured values from the film face andpack bottom face were different, but it was able to obtain respectivelinear regressions showing high correlation with their fracture forces(pack surface: y=6.0648x+3212.1, coefficient of determination 0.9042,pack rear face: y=5.199x+2484.6, coefficient of determination 0.9091)(y: speckle value, x: fracture force value).

In the case of the agar gel, high correlation with fracture force wasobtained from the pack rear face than the film surface (pack rear face:y=1007.7Ln(x)+2772.8, coefficient of determination 0.9119). In the caseof the coffee-containing carrageenan gel, y was 2355.5x^(0.056) andcoefficient of determination was 0.9488 in the pack rear face. In thecase of the albumen gel, y was 507.93 Ln(x)+2547.4 and coefficient ofdetermination was 0.9661 in the pack rear face.

In this connection, it was possible also to distinguish gels havingsufficient hardness from semi-mature to un-coagulated gel (sol) based onthe threshold values shown by continuous or broken horizontal lines inFIG. 4 to FIG. 7.

Example 2

A powdered soybean slurry namago prepared by dispersing 7 kg of finelypowdered domestic soybean (manufactured by Dauichi Tanpaku) in 35 kg ofwater for about 20 minutes using a dispersing machine (KD50-MS,manufactured by Takai Seisakusho) was boiled (5 minutes, 102° C.) usinga soybean milk production plant (NS2000S, manufactured by TakaiSeisakusho) without adding antifoaming agent and then passed through awringer (Sirius Single String manufactured by Takai Seisakusho, a waterflea collecting net: 150 mesh) to obtain about 40 kg of a soybean milkhaving a soybean milk concentration of 11.5% brix. This was cooled withice water until use.

A 3 kg portion of the soybean milk (10° C.) was weighed and mixed with acoagulant solution prepared by mixing 0, 6.7, 13.4 or 15.2 ml of a 1:1by weight bittern solution of a field bittern (manufactured by AkahoKasei) with 3 g of a protein crosslinking enzyme (“Activa” Super Curdmanufactured by Ajinomoto) and adjusting the total volume to 50 ml withwater, and the mixture was immediately filled in a pack for tofu (whiteKyo type, material PP, 350 g) and packaged with a film (material NY/PP,no printing). As a blank, a sample was also prepared by filling andpackaging the soybean milk alone. Thereafter, this was heated in a hotwater bath of 60° C. or 80° C. for 35 minutes and then cooled to be usedas a measuring sample. In this case, another sample was also prepared byheating a sample of 13.4 ml of the field bittern only at 60° C. for 35minutes.

Each of the samples under the packaged state was allowed to stand stillwith its film face upward, and the speckle pattern 6 by the irradiationof the laser beam 2 of 0.78 μm was photographed (measured) using theaforementioned two-dimensional image recognizing system of the scatteredlights 4 and 5. By carrying out the measurement 30 times for one test,primary differential values of the brightness of speckle pattern werecalculated, and the average value of 30 times was used as the specklepattern value.

Thereafter, each sample in the container after peeling off the film wassubjected to the measurement of fracture force using a rheometer(NRM-2002J, manufactured by Fudo Kogyo), sampling evaluation(appearance, color, odor, taste and texture are scored by 10 steps, andthe total is expressed as points out of possible 100) by severalpanelists and measurement of water release ratio based on the differencein weights before and after 2 hours of standing. The results are shownin Table 2 and FIG. 8. TABLE 2 No mark 0 1 2 3 4 5 Bittern addition %0.00 0.00 0.00 0.11 0.22 0.22 0.25 ratio Field bittern g 0.0 0.0 0.0 6.713.4 13.4 15.2 (1:1) Water g 50.0 0.0 50.0 43.3 36.6 36.6 34.8 Enzymeaddition % 0.00 0.00 0.10 0.10 0.10 0.10 0.10 ratio Fracture forcegf/cm² 0.5 0.5 0.0 3.9 83.3 89.4 102.1 Average water % 0.0 0.0 0.0 0.012.3 2.9 11.1 release ratio L 79.9 79.9 79.5 80.5 82.6 82.2 83.2 a −6.7−6.7 −6.7 −6.6 −6.5 −6.8 −6.6 b 15.3 15.5 15.2 15.3 15.0 14.8 14.9 TofupH 6.65 6.66 6.67 6.50 6.34 6.37 6.31 Product soy soy soy semi- hardspring, hard evaluation milk milk milk-like mature soft Speckle value2000 1900 2200 3000 4400 4100 4300

Regarding the hardness (fracture force) which is important fordetermining tofu quality, there was a high correlation between it andspeckle value. When the fracture force was represented by x, and thespeckle value by y, a radical approximate expressiony=2495.813x^(0.1013) (coefficient of determination 0.871) was derived.In addition, as shown by a broken horizontal line in FIG. 8, it was ableto distinguish completely coagulated non-defectives from semi-mature orun-coagulated defectives based on a speckle value of about 3800 as thethreshold value.

Example 3

Beans of a domestic soybean Toyomasari (produced in Hokkaido in 2000)were soaked in well water at 15° C. for 22 hours. A 17.6 kg portion ofthe soaked soybeans corresponding to 8 kg of raw soybeans werepulverized, and the thus prepared namago was mixed with 40 g of anantifoaming agent (Emulsy Super manufactured by Riken Vitamin) andboiled (5 minutes, 102° C.) using a soybean milk production plant(NS2000S, manufactured by Takai Seisakusho) and then passed through awringer (Sirius Single String manufactured by Takai Seisakusho, a waterflea collecting net: 100 mesh) to obtain about 35 kg of a soybean milkhaving a soybean milk concentration of 13.0% brix.

The soybean milk was controlled at 82° C. in a soybean milk tank andpumped out by a metering pump (a rotary pump manufactured by Nakakin)and, on the other hand, an emulsion bitter (MagnesFine TG manufacturedby KAO) was pumped out by a precise metering pump (Mono-Pumpmanufactured by Heishin) at a rate of 0, 1, 2 or 3 L/H, both of themwere combined by a piping system and immediately subjected to a strongdispersion using a static type mixing and stirring device (“TS Mixer”manufactured by Takai Seisakusho) and then immediately thereafter, thedispersion was filled in a pack for tofu (Kyoto type 350 g, PP) andpackaged with a film (NY/PP). Immediately thereafter, using the samplesstill warm under packaged state and the samples under unsealed state bypeeling off the packaging films immediately thereafter, speckle valueswere measured in the same manner as described in the aforementionedExample 2. The results are shown in Table 3 and FIG. 9. TABLE 3 Emulsionbitter Fracture flow rate Sample Speckle value force L/h n = 26 Packagedstate Unsealed state gf/cm² 0.0 1-3 871 1259 0.0 1-4 1040 1012 0.0 1-5904 1345 0.0 1-6 1055 1403 0.0 3.0 2-1 3498 3399 97.1 2-2 3536 3435103.9 2-3 3518 3549 95.2 2-4 3391 3283 95.3 2-5 3287 3504 96.5 2-6 32483337 99.6 2-7 3427 3482 101.5 2-8 3488 3512 96.6 2.0 3-1 3067 3274 62.13-2 3158 3409 61.3 3-3 3049 3369 63.7 3-4 2863 3408 61.6 3-5 2888 331365.7 3-6 3054 3382 64.5 3-7 2616 3208 39.0 1.0 4-1 1224 1710 2.2 4-21187 1612 2.8 4-3 1195 1742 2.2 4-4 1192 1529 2.1 4-5 1142 1748 1.9 4-61165 1857 2.4 4-7 1098 1644 2.2

Although there was a slight difference between the cases of the presenceand absence of the packaging film, there was a high correlation betweenthe fracture force and the speckle value. When the fracture force wasrepresented by x, and the speckle value by y, the multinomialapproximate expression was y=−0.2145x²+45.342x+1034.9 under the packagedcondition, and the coefficient of determination was 0.9914. Under theunsealed condition, the multinomial approximate expression wasy=−0.309x²+50.381x+1462.9, and the coefficient of determination was0.9737. In addition, as shown by solid and broken horizontal lines inFIG. 9, it was able to distinguish completely coagulated non-defectivesfrom semi-mature or un-coagulated defectives based on a speckle value ofabout 2500 under packaged condition, and a speckle value of about 3000under unsealed condition, as respective threshold values.

Example 4

As shown in FIG. 10, the aforementioned scattered reflected lighttwo-dimensional observation system can monitor gelation process of thecontents and gelation condition of the contents. Practically,coagulation process of a soybean milk was periodically measured.

A 12 liter portion of a hot soybean milk 1 (13% brix, 70° C.) preparedas described in Example 3 was put into a polypropylene container box 15(370×370×depth 150 mm, board thickness 10 mm) and, under the followingcoagulation conditions, continuously monitored by the two-dimensionalimage observation device 9 from the start of the coagulation agitation,by arranging the scattered reflected light-observing two-dimensionalobservation system as sown in FIG. 10 on the side face of theaforementioned container box and irradiating the light 2 from thesemiconductor laser beam source 3 at a wavelength of 0.82 μm, andspeckle values with the lapse of time were measured starting from theaddition of each coagulant at every 1 second for 20 minutes (average of30 measurements); on the case of the addition of 36 g of GDL(glucono-δ-lactone, manufactured by Fujisawa Pharmaceutical) dispersedin 200 ml of water, on the case of the addition of 120 g oftransglutaminase (“Activa” Super Curd manufactured by Ajinomoto,contains 0.2% transglutaminase) dispersed in 200 ml of water, on thecase of the addition of 36 g of a clear powder (calcium sulfate, “Pearlα” manufactured by Akaho Kasei) dispersed in 200 ml of water or on thecase of the addition of 96 g of a liquid bittern (crude sea watermagnesium chloride, “Umi-no Megumi” manufactured by Takai Seisakusho,contains 33.2% magnesium chloride), while stirring the milk with thebatch type coagulation device 14 (“MultiCurdy Type S” manufactured byTakai Seisakusho), or on the case of the addition of 120 ml of anemulsion bittern (“Magnesfine TG” manufactured by Kao, contains 33%magnesium chloride) dispersed using a using a static type dispersiondevice (“TS Mixer” manufactured by Takai Seisakusho), effected by usinga continuous coagulation device (“New Curdy” manufactured by TakaiSeisakusho). A process displaying the results for every 20 seconds isshown in FIG. 14.

In this connection, a stainless steel container box having an inspectionhole 18 of a material which can transmit irradiation light may be usedas the container box 15. In addition, when the liquid face is in astatic state, the surface of soybean milk or the surface of tofu may bedirectly observed.

As shown in FIG. 14, the reaction rate of coagulants (coagulationgelation rate of soybean milk) coincided with the order of coagulationrate known by experience in the conventional tofu production, which wasliquid bittern>emulsion bittern>clear powder>GDL >transglutaminase.Also, the values under finally stabilized condition reflected relativedifferences of the hardness of tofu, namely in order of GDL>clearpowder≅emulsion bittern>liquid bittern>transglutaminase, and wellcoincided with their relationship with the fracture force valuesobtained in the same manner as described in the forgoing aftersubsequent water bleaching in a water tank. In this connection, thisexample can be carried out also by the tank having an inspection holeshown in FIG. 11 or the piping shown in FIG. 12 and FIG. 13.

Example 5

Samples of the hot-packed tofu prepared in the foregoing (Example 3) inthe case of perfect heat-sealing of film and in the case of partiallyimperfect sealing were cooled in a water tank and then measured usingthe aforementioned scattered reflected light-observing two-dimensionalobservation system. As a result, the speckle value was about 3500 inaverage in the former case, but the latter case showed an abnormallyhigh value of from 5000 to 6000. Accordingly, it was found that a pinhole can be detected. In addition, when the amount of coagulant in theaforementioned hot-packed tofu was increased by adding an excess amountof 1.5% of the emulsion bittern to soybean milk, the speckle value afteraging showed a slightly high value of from 4000 to 5000 in the samemanner, so that it was able to detect a condition of excess coagulation,so-called “yorisugi”.

Example 6

Speckle value (cubic differentiation average value) of packed tofuprepared in the same manner as in the aforementioned Example 2 by addingvaried amount of GDL to a soybean milk of 11.5% brix was measured understatic condition and excitation condition (excitation at 19 kHz and 2W/cm² by installing a commercially available ultrasonic oscillator onpad), and its relationship with fracture force was examined, with theresults shown in FIG. 19. A high correlation with hardness was obtainedunder the excitation condition rather than the completely staticcondition.

Example 7

As shown in FIG. 15, the linear light 2 was irradiated from the laserbeam source 3, traversing the traveling direction of the aforementionedmaterial body 1, in the state in which the aforementioned material body1 was continuously moving on the conveyer 19, and while theaforementioned material body I was traveling, the lights 4 and 5reflecting from the image formation 20 of the linear irradiation lightand the light 6 of speckle pattern were continuously measured using theaforementioned two-dimensional observation device 9. As a result,distribution of speckle values was obtained on the full face of imageformation face. Based on this, it was able to detect a product in whicha hard moiety shown by an arrow A in FIG. 18 and a soft moiety shown byan arrow B are present on its surface and inner part.

In addition to this, speckle values can be obtained on the almost fullface of image formation face by an embodiment in which spot lights arearranged sideways like the case of FIG. 16 and another embodiment inwhich spot lights are two-dimensionally arranged (at the time ofintermittent moving) like the case of FIG. 17.

While the invention has been describe in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope of the invention.

This application is based on a Japanese patent application filed on Mar.28, 2002 (Japanese Patent Application No. 2002-092979), the entirecontents thereof being thereby incorporated by reference.

INDUSTRIAL APPLICABILITY

According to the method of the invention for evaluating a gel state or asol-gel state change of a material body, which is characterized in thatthe aforementioned material body is a gel shape material body (or food)or a gel-formable sol shape material body (or food), and said materialbody illuminated by a coherent light-illuminating light illuminationdevice is evaluated using a two dimensional image observation systemequipped with a two dimensionally detecting image recognizing means toobserve an image formation of a light beam section or a speckle patternformed on the image formation face, as described in claim 1 and claim 3,semi-coagulated, un-coagulated and the like defective articles can bedistinguished without exception by realizing objective judgment,non-destructive measurement, non-contact measurement, quick measurementand 100% inspection on the change of gel shape material bodies or foodto gelled states (hardness and the like) or sol shapes, or the change ofgel-formable sol shape material bodies or food to gelled states. As aresult, since defective articles are not shipped, occurrence of claims,compensation problems and the like troubles can be prevented. Inaddition, since this becomes a useful index for the production processcontrol, quality control can be precisely carried out so that it becomespossible to confine futile loss to the minimum.

In case that at least a part of the intervening member islight-transmittable as described in claim 2 of the invention, theaforementioned material body is applicable even when it is a packagedproduct or in a tank or piping equipped with an inspection window, sothat it is not necessary to unseal it or to collect the contentsdirectly, and a burden on the quality control and product loss cantherefore be reduced.

By selecting wavelength of irradiation light (e.g., from visible lightto near infrared) as described in claim 4 of the invention, influencesof the packaging material of packaged products, printing, outdoor light(stray light) and water or the like solvent can be prevented to theminimum so that information on not only the surface but also innertissue can be obtained.

As described in claim 5 of the invention, among the aforementionedpackaged products, a defective product in which water is penetrated intoits inner part due to a pin hole or improper sealing and a product inwhich released water is present, due to the presence of a step forcontacting with water, can also be detected so that a burden to theproduct inspection work can be reduced.

By allowing a product and an observation device to move in a relativemanner as described in claim 6 of the invention, full face of theinspection face of a product or almost full face thereof can become theobject, and products having partial abnormalities can also be detectedwithout exception. In addition, quick and 100% inspection also becomeseasy.

1. A method for evaluating a material body by a scattered lightobservation system which observes a gel state or a gel-formable solstate material body illuminated with a coherent light through a twodimensional image recognizing means, characterized in that a gel stateor a change in sol-gel state of said material body is evaluated based onthe conditions of a light section formed on the image forming surface orconditions of the speckle pattern.
 2. The method for evaluating amaterial body according to claim 1, wherein the material body is a gelshape food article or a gel-formable sol shape food article, and itsquality and change in quality are evaluated.
 3. The method forevaluating a material body according to claim 1, wherein a member havingat least a part through which irradiated light can permeate isintervened between the material body and the aforementionedtwo-dimensional light observation system.
 4. The method for evaluating amaterial body according to claim 1, wherein wavelength of theirradiation light is within the range of from visible light to nearinfrared.
 5. The method for evaluating a material body according toclaim 2 4, wherein the released state of water existing in a sealed andpackaged product of the material body is detected.
 6. The method forevaluating a material body according to claim 1, wherein the materialbody is put in a dynamic state.
 7. A device for carrying out a materialbody evaluation method comprising a material body constituting at leastone row in a transverse direction against a moving direction, lightirradiation device which irradiates a light having at least one spotshape or line shape section traversing a moving direction fixed to orseparated from a light irradiation photographing device prepared byarranging at least one of two-dimensional image recognizing means or atleast one of them is moved by a moving means, thereby carrying outscanning measurement of almost full face or full face of each materialbody which can be observed in a photographing direction of thetwo-dimensional image recognizing means.